1. Field of the Invention
The invention relates to a method and to a data transmission system, which is maintained upon the appearance of locally limited error sources in comparison with the full system by systematic exclusion of such error sources.
2. Brief Description of the Background of the Invention Including Prior Art
Sizable data transmission systems in general have to show a high degree of availability. However, in principle, errors reducing the availability cannot be excluded and redundant building components have to be incorporated in order to nevertheless fulfil the requirement of availability. In addition steps have to be taken for the continuous and periodic supervision of the functioning of the provisions.
U.S. Pat. No. 4,048,446 to Hafner et al. teaches an annular, redundant data transmission system, where each subscriber station is braid-like connected to in each case two or more according to the signal path preceding and a corresponding number of according to the signal path following other subscriber stations. Upon failure of one subscriber station or of a transmission line section the substantially in parallel running transmission lines in each case bridge the source of error. Thus upon a locally limited error source no grave interference occurs of the transmission system as such. Only the traffic with the bridged subscriber stations is interrupted.
The reference does not indicate according to which criteria the subscriber stations in each case are connected to their input lines.
Hafner et al. in Proceedings 1976 International Zurich Seminar on Digital Communications, Page D4.1 teach the enhancing of the availability of a loop system by meshing. The various loops shown in this reference have two inputs and two outputs at each station independent of the number of parallel paths. Such limitation can be awkward at times.